The present invention relates generally to the field of material science, and more particularly to triggering the fragmentation of integrated chips using intermetallic reactions.
The fragmentation of many brittle materials can be controlled by introducing inhomogeneous stress fields within the materials. For example, highly stressed glass has been known to fragment into small pieces since the discovery in the 17th and 18th centuries of the phenomenon known as Prince Rupert's drops. The basic mechanism by which fragmentation occurs, however, has only recently been understood using the framework of fracture mechanics. The phenomenon relies on setting up glass in a highly tensile stressed state by containing it in a thick, compressively stressed outer layer. In Prince Rupert's drops this is accomplished by quenching molten glass in water to form glass boules. More recently, it has been shown that ion exchange processing of soda lime glass is another effective way of generating a compressively stressed surface layer.
Intermetallic reactions are exothermic reactions that involve numerous elements such as aluminum (Al), antimony (Sb), barium (Ba), beryllium (Be), bismuth (Bi), boron (B), cadmium (Cd), calcium (Ca), carbon (C), cerium (Ce), cobalt (Co), chromium (Cr), copper (Cu), germanium (Ge), hafnium (Hf), iron (Fe), lanthanum (La), lead (Pb), lithium (Li), magnesium (Mg), manganese (Mn), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), potassium (K), praseodymium (Pr), platinum (Pt), plutonium (Pu), samarium (Sm), selenium (Se), silicon (Si), sodium (Na), strontium (Sr), sulfur (S), tantalum (Ta), tellurium (Te), thorium (Th), tin (Sn), titanium (Ti), tungsten (W), uranium (U), vanadium (V), Yttrium (Y), zinc (Zn), and zirconium (Zr). The term “intermetallic reactions,” which was introduced in the 1950s, has become somewhat of a misnomer since elements from virtually every periodic group except the halogens and noble gases participate in these reactions.
The individual elements used in intermetallic reactions tend to be relatively unreactive. However, strongly exothermic reactions take place when certain pairs of the elements are combined and ignited. Sources of ignition include electrical discharge, flame, mechanical friction, impact, etc. In many intermetallic reactions, oxygen is not required and no gases are produced. The products of many of these reactions are solid-state compounds exhibiting metallic bonding, defined stoichiometry, and an ordered crystal structure. Because of the intense heat generated, intermetallic reactions have found many uses in applications such as welding, bonding, melting, and microelectronics.